(Photo : Kevin C. Cox/Getty Images) A podium with the logo for the Centers for Disease Control and Prevention at the Tom Harkin Global Communications Center.

Frontline essential workers and people over the age of 75 should be next in line to receive a dose of a COVID-19 vaccine, a U.S. Centers for Disease Control and Prevention advisory panel said on Sunday.

CDC's Advisory Committee on Immunization Practices (ACIP) voted 13 to 1 recommending 30 million frontline essential workers and the said age group.

In all, around 51 million people will get the next round of vaccines, said a Reuters report.

Some of the essential workers included in the vaccine recommendation are first responders, teachers and grocery workers.

This is part of the vaccine distribution's Phase 1b. The phase 1c will include people 65 to 74 years old, 16 to 64 year olds with high-risk medical conditions and non-frontline essential workers such as the media IT and communications workers, reported USA Today.

It's not made immediately clear when the next phase would begin or how long the vaccination period will last for each group.

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News of the next priority group came as a second vaccine rolled out to hospitals on Sunday.

According to The Associated Press, about 556,000 shots have already been given to Americans across the U.S.

Earlier this month, the ACIP recommended health care workers and nursing home residents to be the first ones who'll get a vaccine dose. That makes up 24 million people.

Experts Back Decision for Vaccine Priority

There was a high mortality rate in older adults from the 75-year-and-older population and 25% hospitalization, the ACIP said.

Meanwhile, given the limited number of available doses, essential workers were broken down into the two groups: frontline and non-frontline workers.

Those who work at the frontlines were considered as those at higher risk of contracting the virus since they have critical work that requires them to be in contact with numerous people.

"My hope is that these short-term recommendations will support efficiency and equity in every phase of vaccination until we can get to the time when all individuals have access to safe and effective vaccines in the U.S. and worldwide," Dr. Grace Lee, a professor of pediatrics at Stanford University told USA Today.

The ACIP's decision on who gets inoculated first is difficult, noted Dr. Sharon Fry of the Saint Louis University.

The decision demands the committee to have the vaccine given as quickly as possible to the people who are at greater risk of COVID-19 infection or will suffer the most severe outcomes.

"There are no perfect recommendations," she said, as people could still fall ill until the right amount of vaccines is ready.

States will be using the ACIP guidelines in their distribution of shots for  both the Pfizer and Moderna COVID-19 vaccines.

Vaccine Doses to Be Limited in Next Few Months

Federal authorities said that as production is just starting to take shape, vaccine supplies will be limited at first but will ramp up in the coming months.

The first 2.9 million doses for the Pfizer vaccine started going out on December 13.

An additional 2 million is expected to go out this week, alongside Moderna Inc's 5.9 million doses.

Even after the initial distributions, the half of all U.S. health care workers and nursing home residents will still need to be vaccinated.

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